LEGO Part 4558955 - 87087 - Brick 1x1 with 1 Knob Dark Stone Grey | LEGO Bricks, Replacement Pieces and Parts
piece information - LEGO elements working with capacitive touchscreens? - Bricks
87087 LEGO Brick, Modified 1 x 1 with Stud on 1 Side - Parts Pick a Brick LEGO - LEGO Brick, Classic and Modified - LEGO Brick, Modified - Brickshop.it
BrickLink - Part 87087 : LEGO Brick, Modified 1 x 1 with Stud on Side [Brick, Modified] - BrickLink Reference Catalog